Can it happen that all these numbers on vertices are even?
Source: Tournament of Towns Spring 2003 - Senior A-Level - Problem 7
June 15, 2011
combinatorics proposedcombinatorics
Problem Statement
A square is triangulated in such way that no three vertices are collinear. For every vertex (including vertices of the square) the number of sides issuing from it is counted. Can it happen that all these numbers are even?